Fastenal head bolts, part numbers and help.

8

8lugthug

New member
Joined
Jan 4, 2015
Messages
11
I'm sure this has been asked many times before on this form but nobody knows part numbers. I'm not very experienced in metric bolt sizes so all the help will be appreciated!
 
I searched "head bolt size" and got:
12x1.75x70&120.
Easy. Look for that on fastenal/McMaster.
 
Last edited:
Well after looking around for a while I found out these specs...

12mm x 1. 75 thread pitch

six are 70mm long

eight are 120mm long

six are 180mm long

washers

nine are 12mm

five are 10mm use a die grinder to enlarge the center (used between the valve covers)

six long rocker bolts dont get washers
 
Last edited:
You have to machine the Pedestals unless you machine the height of the long bolts. I make up the sets and sell them for 120.00
 
I'm fairly certain that those bolts are closer to a UTS of 120ksi instead of say an A1 H11 at 240ksi.

Unless Fastenal does some cold rolled, high carbon, hardened head bolts.
 
I went the "mighty bolt" route which is just these fastenal fasteners and it worked out for me on one of my previous trucks. It was quite mild though with some injectors and a s300g. I know a ton of people had issues with breaking them though and it made me constantly worry about mine. Stock head bolts overtorqued or studs seems to be the safer route. Of course I had a 12mm arp break in my most recent set luckily during the initial torque where I knew about it!
 
CorneliusRox said:
What's stock? Do you know?
Click to expand...

I do not know, but I have used them for a few years and I have friends that have used them. I have had a couple break on install (2), but if they had not broke buy the time you hit up to 120 ft pounds they hold to 130 and have not had any stretch.
 
Shambo said:
I do not know, but I have used them for a few years and I have friends that have used them. I have had a couple break on install (2), but if they had not broke buy the time you hit up to 120 ft pounds they hold to 130 and have not had any stretch.
Click to expand...

Hmm. I suppose if you're selling them for $120, that'd be pretty great for a budget build.
 
I used them and had them at 145. Non broke or stretched during initial torque, but had one break while removing them for the 625s. Make sure to use extremely hard washers.
 
I use mil Grade SS washers and they have worked well for me.
 
Maybe i'm not understanding something but why would you have to machine the pedestals or the height of the bolt?
 
They hit the webbing in the valve cover. The set I saw awhile back had the Allen head ground down to clear. Just have to be carefull and use a good Allen socket that fits tight and doesn't slip.
 
Shambo said:
I do not know, but I have used them for a few years and I have friends that have used them. I have had a couple break on install (2), but if they had not broke buy the time you hit up to 120 ft pounds they hold to 130 and have not had any stretch.
Click to expand...

Stock bolts are 12.9, same as most socket head cap screws. So you are replacing stock bolts with something equivalent to stock bolts with machining required.
 
I didn't use washers on the rockers didn't effect them. No machining if you go that route. I'd save yourself trouble and just buy a set of 625s.
 
I had a set of the mighty bolts....chucked them into the scrap bin before the engine ever started. 6 of the bolts had stripped the threads before even hitting 90 ft. lbs. Put a set of stock head bolts back in and have had no issues. Headgasket still holding with stock bolts over 75PSI of boost.
 
Anybody know the length of the main bolts? Looking to cross them with some other 14mm head bolt possibly.
 
Yes, I really struggle to see the benefit of going to the mighty bolts. Then to top it off the internal hex isn't that friendly either.
 
You must log in or register to reply here.
Top